Flushing cooling system

[jseabolt]

It's been three years since I bought my 2003 Baja so I think it's about time I replace the antifreeze. On my other cars, I've installed a flush tee in the heater hose going into the top of the engine and backwashed the coolant out the top of the radiator that way.

 

But on a Boxer engine, I have no idea how the coolant is routed on this car. I suppose I could turn the heater valve off start the engine and let the coolant backup in the core and feel which hose is hot and which is cold to determine that way.

 

One heater hose goes into the firewall on the driver's side and connects to a pipe which appears to feed into the intake manifold. The other hose exits the passener side and follows along the other hose but where it connects to the engine, I have no idea. It's buried somewhere.

 

So which hose does the flush tee need to be installed?

 

Also is there a drain on the radiator or do you have to disconnect the lower radiator hose?

 

One thing I was thinking about trying was to backwash the old coolant out, then fill a jug of enough pure antifreeze which would give me a 50/50 mixture. Then connect one of those pumps that goes on the end of a drill and pump the new antifreeze into the motor while pushing the water out the top of the radiator.

 

Then put the radiator cap back on. That way I wouldn't have to bleed the cooling system which is a real pain on one of my other cars. I normally use one of those Lisle coolant funnels on that car.

[Legacy777]

One end of the heater hose hooks up to the coolant crossover pipe on top of the engine. The other end hooks up to a line on the pump.

 

To flush the engine out pretty good, just remove the top and bottom radiator hoses, take the garden hose and put it in the top radiator hose, and that will flush everything out of the engine. It won't really get the heater core.....but if you're that picky, you could just remove the heater core lines and flush it out.

 

I suppose if you want to use the kit. Hook it to the heater core line going to the coolant crossover pipe.

[Andyjo]

I'm about to do the same thing, but i'm installing an engine block heater at the same time. The my haynes manual says there's a drain plug on the radiator, and 2 drains for the engine block. The engine block drain plugs require a 14mm allen bit!! I've gotta' goto the local shop tomorrow to see if i can borrow one....

The instructions pretty much just say drain all the fluid, flush it out w/ a hose and then plug it up, and do what you normally do.

[rooomie]

It's been three years since I bought my 2003 Baja so I think it's about time I replace the antifreeze. On my other cars, I've installed a flush tee in the heater hose going into the top of the engine and backwashed the coolant out the top of the radiator that way.

 

But on a Boxer engine, I have no idea how the coolant is routed on this car. I suppose I could turn the heater valve off start the engine and let the coolant backup in the core and feel which hose is hot and which is cold to determine that way.

 

One heater hose goes into the firewall on the driver's side and connects to a pipe which appears to feed into the intake manifold. The other hose exits the passener side and follows along the other hose but where it connects to the engine, I have no idea. It's buried somewhere.

 

So which hose does the flush tee need to be installed?

 

Also is there a drain on the radiator or do you have to disconnect the lower radiator hose?

 

One thing I was thinking about trying was to backwash the old coolant out, then fill a jug of enough pure antifreeze which would give me a 50/50 mixture. Then connect one of those pumps that goes on the end of a drill and pump the new antifreeze into the motor while pushing the water out the top of the radiator.

 

Then put the radiator cap back on. That way I wouldn't have to bleed the cooling system which is a real pain on one of my other cars. I normally use one of those Lisle coolant funnels on that car.

 

If you do it yourself, use distilled water to mix with the antifreezre.. Keeps limstone build up from forming. A must really if you have hard water.

[Setright]

This is what I suggest:

 

Editted! Addition in bold:

 

 

Having replaced coolant on my boxers many times, I have been searching for the right way to get all the old fluid out and getting as much new fluid in, without having to burp the system for a week after I'm done. I think I have finally cracked it!

 

Draining

 

Drain the radiator as far as possible with the little "faucett", and then detach the lower hose from the radiator. (If you are like me, replace any coolant hoses that you remove, and use stainless steel clamps on the new ones)

Even more fluid will drain from the radiator, and some will drain from the engine block. Detach the upper hose from the radiator, and run clean water through the rad until it comes out of the bottom clear in color.

 

Now, I do not contest that the best way to flush the engine block is by unscrewing the two drain plugs, but these are often seized and could turn into a source of trouble if you strip the threads or if they won't seal tight when you screw them back in. SO, I jack up the rear of the car until the engine block is tilting slight forward, ie. wheels about 6 inches off the ground, unscrew the thermostat housing, and let the old fluid run out through the thermostat opening. (Needless to say, I replace the thermostat gasket)

Run clean water in through the upper hose until clear water comes out of the thermostat opening. Leave the car in this position until it stops dripping water.

 

Remove the expansion tank and flush it, there will be plenty of "snot" in the bottom of it! Rinse the hose too. Install the tank again and fill to the FULL mark.

 

 

Filling

 

Close up the bottom end of the cooling system, ie. thermostat and lower hose. If possible, perform the next phase on a slight incline, car pointing upward.

Get a funnel with about 10 inches of half-inch diameter hose on the end of it and slide this down the upper hose in toward the engine block. I do this because bending the upper rad hose causes it to collapse and that makes pouring coolant into it impossible. Pour your preferred coolant directly into the engine block. Pouring slowly, and pausing along the way will help keep air from being trapped inside the block. It should swallow at about two litres before it starts to rise and threaten to come out of the hose. At that point, attach the upper hose to the rad and continue to fill slowly through the rad cap hole. Once it seems full, start the engine, let it run for twenty seconds and shut it off again. This will dislodge the few air pockets that are unavoidable and the fluid level in the radiator should drop a little after the burp, top it off.

Start the engine again, and let it run until the radiator fan starts running, be patient! When then fan starts running, top off the level in the rad and install the radiator cap - and bleed screw if there is one. During the warm up, a small amount of coolant will spill over the rad filler neck, have a cloth to absorb it.

 

Take the car for a shortish run, just a few miles to get it fully warmed up, and park it on level ground. Check hoses for leaks of course, and let it cool. This will take a number of hours, overnight is good.

In the morning, note the level in the expansion tank, it will probably be a little lower than FULL. Fill to the FULL mark, and you're all set.

 

Obviously, you should check the level in the expansion tank for a few days afterward, but there shouldn't be any problems. Resist the temptation to open the rad cap, this will only interfere.

[jseabolt]

One end of the heater hose hooks up to the coolant crossover pipe on top of the engine. The other end hooks up to a line on the pump.

 

To flush the engine out pretty good, just remove the top and bottom radiator hoses, take the garden hose and put it in the top radiator hose, and that will flush everything out of the engine. It won't really get the heater core.....but if you're that picky, you could just remove the heater core lines and flush it out.

 

I suppose if you want to use the kit. Hook it to the heater core line going to the coolant crossover pipe.

 

Thanks. I thought about buying another hose just in case. Which one of these look like the crossover pipe?

 

http://www.partsamerica.com/ProductList.aspx?parttype=1066&ptset=A&searchfor=Heater+Hose

[Legacy777]

Thanks. I thought about buying another hose just in case. Which one of these look like the crossover pipe?

 

http://www.partsamerica.com/ProductList.aspx?parttype=1066&ptset=A&searchfor=Heater+Hose

 

You see the aluminum thing on top of the engine in this pic?

http://www.main.experiencetherave.com:8080/subaru/images/injectors/DCP_2475.JPG

 

That's the coolant crossover pipe.

[OB99W]

I'm about to do the same thing, but i'm installing an engine block heater at the same time. The my haynes manual says there's a drain plug on the radiator, and 2 drains for the engine block. The engine block drain plugs require a 14mm allen bit!! I've gotta' goto the local shop tomorrow to see if i can borrow one....

The instructions pretty much just say drain all the fluid, flush it out w/ a hose and then plug it up, and do what you normally do.

Yeah, but the instructions always make it sound easy. Read Setright's info, and believe it. After 8-9 years, those block drains may not want to come out very willingly. A trick that sometimes (and I do mean sometimes) helps is to have the block warm, but cool the plug with a shot of aerosol penetrant or the like. The idea is to shrink the plug slightly while the block is expanded from the heat, hopefully breaking any bond due to corrosion. Be careful not to hit the block with the spray, especially if you've already drained the coolant, because it will be less tolerant of a rapid temperature change. Maybe a block heater isn't that important .

 

Of course, as has been noted here often, getting all the air out of the cooling system is critical. I've lost count of how many times I've heard or read "Everything was fine until the coolant was changed, but now its overheating.", or worse.

 

--OB99W